Color cinematography



F eb. 14, 1933.

, l COLOR CINEMATOGRAPHY Filed July 2l, 1950 |I|l|'lllIIIINIIIIIWIIIIIWIIIIIWIIIII"'IIIIITIIIWIIIIWIIIIIFiI' Illlllli..

IFI/g2 John G. Ccyosaf;

J. G. cAPsTAr-F 1,897,837

Patented Feb. 14, 1933 UNITED STATES PATENT OFFCE JOHN G. CAPSTAFF, F ROCHESTER, NEW YORK, ASSIGNOR TO EASTMN KODAK COMPANY, 0F ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK coton CINEMATOGRAPHY Application led July 21,

This invention relates to photography and i more particularly to the taking of motion pictures in color.

According to one method of preparing mov tion pictures in color, the picture is taken von twosuperimposed films each sensitized for a different regionof the spectrum, preferably to one of the primary colors such as red or green. The two negatives thus prepared may then be used in the well-known manner to prepare a colored positive film. In the taking of such motion pictures on superimposed films it is of utmost importance that optical contact be maintained between the adjacent lm surfaces while theyare being exposed in the camera, since otherwise the light rays, which are somewhat diffused in passing through the emulsion of the first film, will form a poorly defined image on the second emulsion.

To overcome this diiiculty, it has been proposed tomodify the motion picture camera using such films by attaching to the gate thereof a ressure block which forces the two lms into engagement.' Such an arrangement, however, tends to complicate the structure of the camera and introduces an undesirable drag on the two ilmsdue to the applied pressure.

In accordance with the present invention', it is proposed to maintain the desired intimate contact between the superimposed films without the need for such a pressure block, and to .obtain this result merely by shaping the films transversely thereof in such a manner that they tend to engage each other closely during exposure. This result is achieved by using films that have been given a slight transverse curvature in the process of manu- 4 facture, more particularly this slight curva-A ture is in the form of a slight convexity on the emulsion sides of the films. Thus whenl the edges of such films are forced into engagement during passage through the camera, their entire surface will be in intimate contact at the area of exposure.

For a clearer understanding of the invention reference is made to the drawing in which Fig. 1 is a plane view of a film strip coated with emulsion sensitized to 'one 1930. Serial N0. 469,507.

color and also showing a cross section thereof. Fig. 2 is a similar plane view and cross sectional view of a film strip coated with emulsion sensitized to another color. Fig. 3

is an exaggerated cross sectional view showing the relation of these two film strips when threaded into a camera with their emulsion surfaces in engagement; and Fig. l is a per spective view of a portion of a camera showing means therein for holding the edges of e( the two film strips in engagement.

Referring to Fig. l, 5 generally designates a piece of film strip comprising a support 6 coated with a layer 7 of emulsion which is sensitized to one color such as red. Fig. of 2 represents a piece of film strip generally designated 8 comprising a support 9 coated with an emulsion l() sensitive to a second color such as green. It will be noted from the sectional views of Figs; 1 and 2 that T each film has an arcuate surface with its emulsion side slightly convex. This convexity of the emulsion surface may be obtained by molding the support or hy causing the side of the support opposite the 7 emulsion to shrink while the emulsion surface thereof is uneffected.

In using the present film for taking colored pictures the films 5 and 8 are threaded through a motion picture camera with the 8 emulsion surfaces 7 and l0 facing each other as indicated in Fig. 3. The camera is provided with two fralnimr members l1 and 12, oneof which is preferably movable to ward the other so that the edges of each E frame of the film strips are held tightly in engagement in front of the lens 13 of' the camera. Due to the convexity ot the films 5 and 8, when pressure is applied to the'two edges thereof, tending to latten them, their center portions ,will be forced into intimate contact on account of the natural resistance of the iilm's to the applied force. In this manner the two hnv strips are held in optical contact without complil cated pressure mechanism.

The present disclosureis merely descriptive of one form of applicants invention, and it is to be understood that there may be many modifications and variations within the scope of the pending claims without departing from the inventlve concept.

What I claim is:

1. The method of maintaining two superimposed lm strips with their engaging surfaces in intimate contact which comprises shaping said strips with their nearest surfaces convex, and forcing the edges of the strips into engagement.

2. The combination with two' ilm strips each coated with emulsion, the emulsion of one strip being sensitized to one color and the other being sensitized to another color, said strips being convex on their emulsion sides, of means for holdingthe edges of said strips in engagement.

3'. In a process for making motion pictures in color that includes passing two ditA ferentially sensitized film strips through an exposure gate with their emulsion faces in Contact, the improved method of maintaining the surfaces intimately in contact that comprises forming each film strip with a permanent transverse bow convex .to its emulsion surface and holding the borders of the strip in contact during such passage.

Signed at Rochester, New York5 this 15th day of July, 1930.

JoHN e. CAPSTAFF. 

